U.S. Pat. Nos. 3,501,401 and 3,709,818 describe a method of regeneration of the anion exchange resin portion of a mixed bed condensate demineralizer with caustic followed by contacting the anion exchange resin bed with a calcium hydroxide solution. This substantially reduces sodium ion leakage into condensate water effluent due to replacement of sodium ions from cation exchange resin particles entrained in the anion exchange resin on separation of the mixed bed. This invention requires the use of sufficiently pure and clear dilute calcium hydroxide solution free of suspended solids, which is extremely difficult to prepare due to the impurities present in commercially available lime. These impurities may be either dirt, sand, and other particulate matter, or calcium carbonate formed during storage due to adsorption of carbon dioxide from the atmosphere. If a clear lime solution is to be made from commercially available hydrated lime, one must filter the final dilute lime solution. However, filtering has not been always effective due to either the impurities being colloidal in nature or so excessive as to cause plugging of the filter media in a very short time. The filters on occasion have allowed some insolubles to pass through, thus contaminating the ion exchange resin.